Low-water alarm



c. A. KOTHE.

LOW WATER ALARM.

APPLICATION FI LED FEB- 2h I921.

Patented July 318, 1922;

v M WWW 1M5. 3% M J J.

CHARLES A. KOTI-IE, OF GA'LION, GHIO.

LOlV-WATER ALARM.

Application filed February 21, 1921.

T 0 all whom it may concern:

Be it known that 1, CHARLES A. Korea a citizen of the United States, residing at Galion, in the county of Crawford and State of Ohio, have invented a certain new and useful Improvement in Lowater Alarms, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

My invention relates to that type of low water alarm in which a fusible element is placed adjacent the crown sheet of a boiler and normally closes a conduit from the steam supply to an external alarm adapted to be operated by steam. The fusing of the element accordingly results in an actuation of the alarm. Such devices have been found to be of great utility in preventing explosions due to low water, as the consequent rise in heat of the high part of the crown sheet is communicated to the fusible member and thus the alarm calls the attention of the engineer to the necessity of immediately injecting water into the boiler. Such a device must be arranged to operate before the actual danger point has been reached. It is, therefore, one of the objects of my invention to provide such a device which shall be unfailing in its action, and operate as early as possible in the development of the dangerous condition.

In former practice in low water alarms .in which a fusible element is employed, this element has been sometimes secured to the boiler so as to directly communicate there with adjacent the crown sheet. Such a construction has at least two serious disadvantages in that the scale deposited as the water evaporates is likely to so encrust the openings as to prevent the passageof steam and the sounding of the alarm when the fusible member is melted. And secondly if the alarm is not clogged, the steam adjacent the crown sheet is not only very wet itself but will also carry additional water to the alarm when the fusible member is melted. the alarm is placed near the engineer, he will be scalded by the water which will be thrown out with great force.

It is, therefore, another object of my invention to provide a low water alarm of the fusible element type wherein this element shall be entirely protected from encrusting scale, although the element is placed adjacent to the crown sheet.

Another object of my invention is to con- Speeification of Letters Patent.

Now if Patented July 18, 19223.

Serial No. 446,922.

nect the alarm in such a manner through the fusible element that when this element fuses only dry steam is allowed to pass to the alarm.

Another object of my invention is to provide a safety device which may be readily removed from the boiler for inspection or repair.

Further objects of my invention will be apparent in the course of the following description and the features of novelty will be pointed out in the claims:

In the accompanying drawings in which an embodiment of my invention is illus trated, Fig. 1 is a fragmentary side elevation partly in section of a boiler equipped with a device embodying my invention; Fig. 2 is a longitudinal section on an enlarged scale through the device showing its position in the boiler; Fig. 3 is a view on an enlarged scale of the double bored pipe as it would appear if out through on a central longitudinal plane; Fig. 4 is a detail of a portion of Fig. 2 on the same scale as Fig. 3. Fig. 5 is a section in line 55 of Fig. 2 on an enlarged scale.

The device in general comprises a fusible plate connected adjacent the crown sheet of the boiler but entirely protected from the steam and water adjacent this point. The fusible plate serves as an obstruction preventing communication between a pipe connection. running from the steam dome. and a pipe connection running to the alarm, until the plate is weakened by heat or actually fuses.

Referring to the parts by numerals; the member 10 represents the crown sheet of a boiler, 11 is the outer shell of the boiler, 13 represents the steam dome of the boiler.

The fusible plate 20 should be made of a material which will fuse at a temperature below what will constitute the danger temperature in the crown sheet of the boiler, and for this purpose I prefer to make the plate of tin, which will fuse at a temperature in the neighborhood of 446 F.

The melting temperature of tin is above that which should exist in the crown sheet when it is properly covered with water, since the highest temperature attained by water in a steam boiler is not greater than 390 F. Therefore, a tin plate will constitute an element which will not melt while the boiler is properly filled, but will weaken and melt to sound the alarm before there is any danopening 2 ger of the explosion of the boiler. i l hen, the alarm sounds, therefore, the engineer may start the injectors working at once without danger to the boiler.

The pipe 30 has the two longitudinally entendii'ig' openings 51 ant 32 cored out theref o. and extending through the lower end of the pipe. The plate is secured to this end of the pipe so that the openings 31 and con'iuuur to with the upper face of the plate. Pro cting; ribs 39 may be provided on the pipe surrounding these openings and adapted to project into the plate to firmly hold it in position. as clearly shown in Figs. 2 and 4:. These projections serve to insure a steam tight fit between the pipe and plate so as to prevent escape of steam until the plate is weakened or melted by heat.

lu order to hold the pipe in place with the plate 20 adjacent the crown sheet of the boiler, and also to serve a protecting casin I for the plate. I provide a sleeve 14L which has exterior pipe threads formed thereon, whereby it may be secured in place in the crown sheet. The upper end of this member has interior threads in which the lower threaded end of the pipe is adapted to be inserted. i

The member 14 has internal threads in its central portion. adapted to receive a retaining member 21. This member has a recess formed on its upper face in which the plate 201's adapted to seat. In using); the word plate. I refer to a member considerably smaller in thickness than in its other dimensions. While l do not confine myself to any particular dimensions. l have accomplished very satisfactory results with a plate in the form of a disk ll inches in diau'ietcr and inch thick.

lVhen the rel:

iiniug member .2 is secured in position it abuts the outer edge of the plate 20 and serves to force it securely against the ends of the pipe 30 and the stillness of the plate holds it in position at the center. In the central portion of this upper ace the further recess 22 which provides (fl'iiili'lllli beneath the central portion of the 3 late F20. A suitable non-circular socket 24. may be provided in this member for facilitating its manipulation by a suitable tool. The recess 22 has preferably a small & conununicatino; therewha and affording communication with the interior of the box to allow escape of the tin when plate 20 melts.

From the fore oing description it will be apparent that the plate 20 is completely protected by the member 14: from all encrustelionsv Such encrustations may be deposited in large quantities upon the crown sheet and the exterior of the member 14: as shown at 15. as the water in the boiler evaporates.

The bore 31 is suitably connected. with the steam dome of the locomotive while the bore 32 is suitably connected with the alarm 40. which may preferably take the form of a whistle.

in order to provide communication between the bore and the alarm the upper end of the pipe 230 may be threaded to receive either the alarm lO direct, or to be connected with suitable pipe communicating; with the alarm, if it is desired to place the alarm in some more distant position such as in the cab of the engine.

I have shown suitable packing device l1. allow passage of the pipe through the shell 11 of the boiler and prevent escape of steam at that point.

The communication of the bore 31 with the steam dome may conveniently be made by providing a transverse threaded opening; 34 communi itine' with this bore 31. This opening' may receive the threaded nipple of a suitable pipe coupling- 4-2 provided with a suitable pipe line lfl which communicates preferably with the steam dome It will be understood that this bore may be connected with some other portion of the boiler but should preferably be connected to a portion which will be occupied by dry steam.

"t will be evident that when the water level lecomes so low as to leave the crown sheet uncovered or nearly so, the heat from this sheet will be quickly communicated to the plate 520. Since this plate is made of material which fuses at a temperature be low the danger point, and since it will weaken slightly before it actually fuses to such an orient as to bend into the recess 22,, it will allow escape of steam to the whistle in time .10 that the alarm will be sounded before heir is any danger of explosion of the boiler and when itsounds the engineer may start the injectors to work to supply the ueeijled water to the boiler without danger.

it will also be seen that the plate 20 will not he forced upward into the alarm either while the plate is in its solid form or after it fused so that the alarm can not he clou ed. The seam pressure instead of forcing the plate upward will force it downward into the recess when the plate eakens. and as it melts. the material may finally drop through an opening 93 into the firebox. This construction absolutely prevents clo ning; of the alarm which was likely, to occur in many of the devices formerly used. in which the material of the fusible plug was oftenforced upwa d so as to plug the alarm and prevent its operation.

This arrangement which allows the sounding of the alarm before actual. fusion of the plate 20 constitutes a decided advai'itage in my construction since it absolutely insures the sounding of the alarm before the water has become so low as to endanger the boiler.

Another decided advantage of my device consists in the ease with whichv it may be removed from the boiler for inspection and replacement. It will be seen that all that is necessary is to unscrew the member 21, and the plate 20 may then be readily pried off the end of the pipe, if it does not loosen with member 21.

A. new plate may then be inserted if necessary or the old. one replaced after inspection and in either case the plate may be lightly hammered into place on the pipe. The insertion of the member 21 will then restore the device to its operative condition. The ease of removal of the device is important, since the regulations require monthly inspection of the low water alarm on each locomotive. It will be noticed that the projections 33 will insure steam tight connection between the member 30 and plate 20 and assist in preventing leakage of steam from bore 32 to bore 31.

Is should also be noticed that the plate 20 may be removed as soon as the steam pressure is down without draining water from the boiler, since the pipe 31 communicates with the boiler above the water line. This reduces the time required to effect the examination of the safety device and to put the engine back into service.

Another advantage of my construction is that the casing 14;, not having its interior open to the water in the boiler, constitutes in effect a heating chamber conveying the heat of the crown sheet directly to the fusible element. The result is that when the water in the boiler falls to a lower level than the fusible element though not sufliciently to uncover the crown sheet, the surrounding steam being unable to carry away the heat from the upper portion of the casing, the element becomes heated by conduction sufficiently to release the alarm. Accordingly with the same height of casing 14; I cause the alarm to operate with a materially higher water level than if the casing had openings to the water space.

While I have described a device embodying the principles of my invention, it is ap parent that many other forms of device embodying these principles may be made, and therefore the foregoing description is to be taken as illustrative of a particular embodiment of my invention rather than as restrictive of its character and scope.

Having thus described my invention, I claim 1.' In a low water alarm, a fusible plate,

' pipe connections connecting with separated points on one face of said plate and sealed thereby, and connected at their other ends respectively with the interior of the boiler and with an alarm operable by steam release by the bending of said plate.

2. In a devlce of the class described, a

steam boiler, a thin fusible plate having a thickness less than either of its other dimensions, means for holding said plate adjacent the crown sheet of the boiler, pipe connections communicating with separated points on one face of said plate andsealed thereby, the other end of said pipe connections communicating respectively with a supply of dry steam and an alarm.

3. In a device of the class described, a steam boiler, a thin fusible disk having a thickness considerably less than its diameter, conduits leading from the same side of the disk to an alarm and to the interior of the boiler respectively, and means for holding said disk against the ends of said conduits whereby communication between the con duits is cut off.

4. In a device of the class described, a steam boiler, a fusible disk, means for holding said disk adjacent the crown sheet of the boiler, pipe connections communicating with separate points on one face of'said disk and sealed thereby, the other end of said connections communicating respectively with an alarm and with the interior of the boiler, and supporting means for holding said disk on the ends of said conduits, said means leaving the disk unsupported for the greater part of the area opposite the con duits.

5. In a device of the class described, a steam boiler, a fusible plate, pipe connections having communication with separate points on said plate, said fusible plate being held in" a closed casing carried by the crown sheet,

communicating with separate points onone face of said plate, said fusible plate being held adjacent the crown sheet and sealing said pipe connections, said plate being unsupported opposite said points of connection, the other end of said bores being connected respectively with the steam dome and an alarm, and a protecting casingsurrounding said plate and protecting it from the steam and water adjacent the crown sheet.

7 In a low water alarm, a pipe connection having a cylindrical exterior and two longitudinal bores extending through one end thereof within the boiler, said connection extending through the wall of the boiler, a stufling box embracing said connection and inserted in said wall, saidbores each having communicating beyond the boiler, and a thin fusible plate connected to the end of the pipe within the boiler to seal the end of the bores.

8. In a device of the class described, a pipe connection having two longitudinal bores extending through one end thereof,

projecting ribs on the end of the pipe and surrounding said bores, said bores each communicating at another place with the exterior of said connection and a fusible plate connected to the end of the pipe and having said projections seated therein to seal the bores.

9. In a device of the class described, the combination of two conduits terminating side by side, a fusible plate extending across the ends of the conduits with one face sealing said conduits and normally preventing communication between them, and a supporting member engaging the opposite side of said plate while leaving a space into which the plate may bend.

10. In a device of the class described, a pipe connection having two longitudinal bores extending through one end thereof, and having communication with the exterior of the connection at another place, and a fusible member connected to the end of the pipe to seal the bores, a'casing member removably secured on the lower end of said pipe surrounding said fusible member, and a member removably mounted in said casing and abutting the opposite side of said fusible member.

11. In a device of the class described, the combination of two conduits having their ends side by side and a fusible member positioned at the ends of said conduits to seal them, a casing member secured to the conduits and surrounding said fusible member, a member removably secured in said casing and abutting the outer portion of said fusible member and having a recess substantially opposite the ends of the conduits.

12. In a device of the class described, the combination of two conduits having their ends terminating flush with each other and side by side, a fusible plate having one face extending across the ends of said conduits to seal them, a casing secured to the conduits and surrounding said fusible member, a member movably secured in said casing and having an annular portion forming a sup port abutting the fusible member outside of the ends of the conduit and having a recess opposite said ends.

13. In a device of the class described, a boiler, a pipe connection having two longitudinal bores extending through one end thereof, two annular projections on the end of said pipe conection surrounding the open ings respectively, a fusible plate adjacent the crown sheet and covering said end, and hav ing the said projections seated therein, the other ends of said pipe bores being connected respectively with the steam dome and an alarm.

14. In a device of the class described. a steam boiler, a fusible plate adjacent the crown sheet thereof, pipe connections communicating with two adjacent points on the face of said plate and sealed thereby, the other ends of said pipe connections being connected respectively with the steam in said boiler and an alarm, the central portions of the underside of said plate being unsupported to allow warping of the plate for passage of steam to said alarm slightly before the plate melts.

15. In a device of the class described, a steam boiler, a fusible plate, pipe connections having communication with adjacent points on one face of the plate, the other end of said pipe connections leading respectively to the steam dome and an alarm, a member abutting the other side of said face and having a recess adjacent the central portion thereof, whereby the plate may bend into said recess as the plate weakens to provide steam communication between said pipes.

16. In device of the class described, a steam boiler, a fusible plate adjacent the crown sheet thereof, pipe connections communicating with one face of said plate and sealed thereby, said connections extending respectively to an alarm and to the steam dome, member abutting the outer edge of the other face of said plate and having a recess adjacent the central portion of the plate whereby said plate may bend into said recess to allow passage of Steam to the alarm l:- ore the plate fuses, means for holding said member in place and a casing-for pro tecting said plate from the steam and water adjacent the crown sheet.

1'7. In a device of the class described, a steam boiler, a fusible plate adjacent the crown sheet thereof, pipe connections communicating with one face of. said plate and havi' projections seated in. said plate, whereby said plate seals said connections, the other ends of said connections extending respectively to an alarm and to the steam dome, a member abutting the outer edge of the other face of said plate and having a recess adjacent the central portion of the plate whereby said plate may bend into said recess to allow passage of steam to the alarm before the plate fuses, means for holding said member in place and a means for protecting said plate from the steam. and

water adjacent the crown sheet. 1

18. In a device of the class described, a steam boiler, a pipe connection having two longitudinal bores extending through one end thereof, a fusible plate covering said end, and a member adapted to hold said end adjacent the crown sheet of the boiler, said member being internally threaded, and a supporting member inserted in said threads and adapted to abut the outer portion of said plate, and having a chamber beneath the central portion thereof, said bores communicating respectively with the steam dome and an alarm.

19. In a device of the class described, a

steam boiler, a pipe connection having two longitudinal bores extending through one end thereof, a fusible plate covering said end, and a member adapted to hold said end adjacent the crown sheet of the boiler, said member constituting a casing for protecting said plate from communication with the boiler adjacent the crown sheet, being internally threaded, and a supporting member inserted in said threads and adapted to abut the outer portion of said plate, and having a chamber beneath the central portion thereof, said bores communicating respectively with the steam dome and an alarm.

20. In a device of the class described, a boiler, a pipe connection having two longitudinal bores extending through one end thereof, a projection surrounding each opening, a fusible plate covering said end, and having the said projections seated therein, the other ends of said pipe bores being connected respectively with the steam dome and an alarm, means surrounding said plate and adapted to hold the pipe end adjacent the crown sheet, and a member carried by said means and abutting the edge of said alate to hold it in position on said pipe and laving a chamber adjacent the central portion thereof.

21. In a device of the class described, a

a steam dome and alarm, means surroundin said plate and adapted to hold the pipe adjacent the crown sheet of the boiler, a member carried by said means and abutting the edge of said plate and having a chamber at the central portion thereof.

22. In a low water alarm, the combina tion with conduits leading from a steam space in the boiler and to an alarm respectively, of a fusible element controlling communication between such conduits, and a heating chamber carried by the crown sheet and supporting such fusible element out of contact with the surrounding water in the boiler, said chamber comprising a casing with a closed wall and a screw plug within the casing in immediate contact with the wall thereof and positioned to convey heat from the crown sheet substantially directly to the fusible element.

23. In a low water alarm, the combination with a conduit from a steam supply and a conduit to an alarm, said conduits terminating side by side, a fusible element extending across said conduits and adapted to prevent communication between said conduits, a hollow casing secured to the crown sheet of the boiler and connected with said conduits, and having a closed wall preventing communication from the surrounding water space in the boiler to the interior of the, casing whereby said casing may constitute a heat ing conveyor from the crown sheet to the fusible element, while there is still a material amount of water above the crown sheet.

In testimony whereof, I hereunto aiiix my signature.

i CHARLES A. KOTHE. 

